Air filtration device including filter change indicator

ABSTRACT

An air filtration device for intake of atmospheric air, removal of contaminants from the atmospheric air, expulsion of filtered air, includes a housing configured for application directly to an electrical outlet and provides air intake from the front surface of the housing and air expulsion from the side of the housing to utilize a wall surface to disperse the filtered air. A filter change indicator is provided to communicate that a filter should be changed, and a filter orientation system is provided to allow proper orientation of the filter with respect to air flow.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of copending U.S. patent application Ser. No. 09/563,821, filed May 3, 2000.

BACKGROUND OF THE INVENTION

The present invention related broadly to air filtration apparatus and, more particularly, to an air filtration device that is configured for abutment against an electrical outlet providing operational power for the device, with atmospheric air flowing into an intake on the front surface of the device, and filtered air being emitted through vents provided on the side of the device.

As the atmosphere in general becomes more polluted and the general population becomes more aware of discomforts associated with dirty air, air filtration devices of all shapes, types and sizes have become more popular. One type of air filtration device provides a small fan for use in a smoky environment. These devices typically will include an electric fan contained in a small housing for tabletop use, with a filter through which the air is directed for removal of smoke and other such contaminants. These small fans are useful for removing odors and contaminants from a confined space, since they typically take up little space themselves and move a relatively small volume of air.

Such current designs, while effective, leave room for improvement in the areas of noise control, air dispersion and filter management.

SUMMARY OF THE INVENTION

An air filtration device is provided for intake of atmospheric air, assistance in removal of contaminants from the atmospheric air, expulsion of filtered air and configured for operational association with a generally vertically oriented surface. The device includes a housing defining an air flow path therethrough having a front surface, at least one side surface and a rear surface; at least one air inlet formed in the front surface of the housing; and at least one air outlet formed in the housing intermediate the front surface and the rear surface, for cooperation of the air outlet with a generally vertical surface to which the air filtration device is associated for enhanced dispersion of filtered air expelled through the air outlet. A filter is mounted to the housing in the air flow path and an impeller is provided for moving air through the housing along the air flow path from the at least one air inlet to the at least one air outlet, with the impeller being mounted to the housing.

The air outlet may be formed on the at least one side surface and the air flow path may be defined from the air inlet on the front surface through the filter, through the impeller and outwardly through the air outlet. Also, the side surface may be curved and the air outlet may be formed as a series of vents along the curvature of the side surface.

The air filtration device may further include a bumper member attached to the rear surface of the housing for abutment with a generally vertical surface to which the air filtration device is associated for orientation of the device with the vertical surface. The bumper member may also be formed from resilient material for enhanced noise reduction when the air filtration device is in operation. The filter can be formed as a generally planar member selectively removable from the housing and can include a notch formed therein for directing insertion of the filter in a correct orientation with respect to the air flow path. The housing may include a locating surface formed thereon and corresponding with the notch in the filter to orient the filter in the housing. The housing may also include an icon formed thereon at a position corresponding with the notch in the filter when the filter is inserted in the housing for enhanced visual indication of proper filter orientation.

The air filtration device can include an electric motor for driving the impeller and a pair of electric prongs extending outwardly from the rear surface of the housing for operational engagement with an electrical wall outlet for supplying electric power to the electric motor. The pair of electrical prongs can be configured with each prong in the pair having substantially the same dimensions, so that said air filtration device may be connected to an electrical outlet without regard to the dimensional differences between the socket openings.

The air filtration device may further include an indicator for communicating that the filter should be changed, the indicator providing information after a predetermined period of operation of the air filtration device has passed. The impeller may be driven electrically and the indicator can include an electric timer circuit operationally associated with the impeller for determining when a predetermined time of impeller operation has passed.

A lamp may be mounted to the housing for illumination when the impeller is in operation, with the lamp being in electrical communication with the electric timer circuit and configured to provide pulsating illumination when a predetermined time of impeller operation has passed. A reset switch can be provided in electrical communication with the electric timer circuit to selectively reset the electric timer circuit to a zero operational time setting.

In an alternative embodiment of the present invention, the indicator may comprise an indicator member movably supported by the housing. The indicator member most preferably includes a date wheel rotably supported by the housing and having an annular indicia ring. Indicia are supported by the annular indicia ring for selective rotational positioning relative to the housing at one of a plurality of set positions, wherein each indicia indicates time and is associated with one of the set positions. An indexing device is operably associated with the date wheel for rotationally and releasably retaining the wheel in one of the plurality of set positions. The rotational positioning of the date wheel relative to the housing provides an indication of when the filter should be replaced.

It will be understood by those skilled in the art that variations on that which is described above may be achieved by addition or omission of the features of the features above described.

Accordingly, an air filtration device is provided for intake of atmospheric air, assistance in removal of contaminants from the atmospheric air, expulsion of filtered air and configured for operational association with a generally vertically oriented surface, and includes a housing for abutting attachment to an electrical outlet, the housing defining an air flow path therethrough and having a front surface, at least one side surface and a rear surface; at least one air inlet formed in the housing; at least one air outlet formed in the housing intermediate the front surface and the rear surface; a filter mounted to the housing in the air flow path; an electrically driven impeller for moving air through the housing along the air flow path from the at least one air inlet to the at least one air outlet, with the impeller being mounted to the housing; and a pair of electric prongs extending outwardly from the rear surface for operational engagement with an electrical wall outlet for supplying electric power to the impeller. The pair of electrical prongs can be configured with each prong in the pair having substantially the same dimensions, so that said air filtration device may be connected to an electrical outlet without regard to the dimensional differences between the socket openings. A bumper member is attached to the rear surface of the housing for abutment with a generally vertical surface to which the bumper member may abut for orienting the device with the vertical surface. The bumper may be formed from resilient material for damping vibrations received from the housing to provide enhanced noise reduction when the air filtration device is in operation.

The air filtration device includes an air inlet that is formed on the front surface of the housing and the air flow path is defined from the air inlet on the front surface through the filter, through the impeller and outwardly through the air outlet. The filter may be formed as a generally planar member selectively removable from the housing and includes a notch formed therein for directing insertion of the filter in a correct orientation with respect to the air flow path. The housing may include a locating surface formed thereon and corresponding with the notch in the filter to orient the filter in the housing. The housing may include an icon formed at a position corresponding with the notch in the filter when the filter is inserted in the housing for enhanced visual indication of proper filter orientation.

The air filtration device may include an indicator for communicating that the filter should be changed, the indicator providing information after a predetermined period of operation of the air filtration device has passed. The impeller may be driven electrically and the indicator may include an electric timer circuit operationally engaged with the impeller for determining when a predetermined time of impeller operation has passed. The air filtration device also can include a lamp mounted to the housing for illumination when the impeller is in operation, the lamp being in electrical communication with the electric timer circuit and configured to provide pulsating illumination when a predetermined time of impeller operation has passed. A reset switch can be provided in electrical communication with the electric timer circuit to selectively reset the electric timer circuit to a zero operational time setting. The indicator may alternatively comprise a date wheel rotatably supported by the housing and including indicia comprising symbols indicative of time for providing an indication of when the filter should be replaced.

It should also be understood that the above-described features may be combined under a single, full-featured unit. In that regard, an air filtration device for intake of atmospheric air, removal of contaminants from the atmospheric air, expulsion of filtered air and configured for operational association with a generally vertically oriented surface, includes a housing for abutting attachment to an electrical outlet, the housing defining an air flow path therethrough and having a front surface, a curved side surface and a rear surface; at least one air inlet formed in the front surface of the housing; and a series of vents formed in the side surface intermediate the front surface and the rear surface, for cooperation of the vents with a generally vertical surface to which the air filtration device is associated for enhanced dispersion of filtered air expelled through the vents. A filter is mounted to the housing intermediate the at least one air inlet and the at least one air outlet, with the filter being formed as a generally planar member selectively removable from the housing and including a notch formed therein for directing insertion of the filter in a correct orientation with respect to the air flow path. The housing may include a locating surface formed thereon and corresponding with the notch in the filter to orient the filter in the housing. An electrically driven impeller is provided for moving air through the housing along the air flow path from the at least one air inlet to the vents, with the impeller being mounted to the housing. A pair of electric prongs extends outwardly from the rear surface for operational engagement with an electrical wall outlet for supplying electric power to the impeller. The pair of electrical prongs can be configured with each prong in the pair having substantially the same dimensions, so that the air filtration device may be connected to an electrical outlet without regard to the dimensional differences between the socket openings. A bumper member is attached to the rear surface of the housing for abutment with a generally vertical surface to which the bumper member may abut for orienting the device with the vertical surface. The bumper member may be formed from resilient material for damping vibrations received from the housing for enhanced noise reduction when the air filtration device is in operation.

The air filtration device may include an indicator providing information after a predetermined time period of operation of the air filtration device has passed. The indicator may include an electric timer circuit, as described above, to determine how long the impeller has been in operation and, when the time period has passed, an indicator lamp provides a pulsing illumination. The electric timer circuit may also be provided with a reset switch to selectively reset the electric timer circuit to a zero operational time setting. Alternatively, the indicator may comprise a mechanical date wheel for manual rotation relative to the housing, as described herein.

By the above, the present invention provides an air filtration device that will plug directly into an outlet and utilize the wall behind the device for dispersion of filtered air, while directing air intake from a central source. The present invention also provides a handy visual indication of when the filter is placed in proper orientation with respect to air flow. Further, the device provides reduced noise by damping vibrations transmitted from the housing to the wall against which the device is mounted. Finally, the present invention provides a filter change indicator for providing a convenient visual indication of when the filter should be replaced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an air filtration device according to the preferred embodiment of the present invention;

FIG. 2 is a front view of the air filtration device illustrated in FIG. 1;

FIG. 3 is a rear view of the air filtration device illustrated in FIG. 1;

FIG. 4 is an exploded view of the air filtration device illustrated in FIG. 1;

FIG. 5 is a cross-sectional view of the air filtration device taken along line 5—5 in FIG. 2;

FIG. 6 is a cross-sectional view of the air filtration device similar to line device in FIG. 5, illustrating an alternate embodiment without a timer circuit;

FIG. 7 is a side view of the air filtration device illustrated in FIG. 1, shown mounted to a wall;

FIG. 8 is a rear view of the air filtration device as illustrated in FIG. 3, shown mounted to a wall;

FIG. 9 is a front perspective view of the air filtration device illustrating filter placement;

FIG. 10 is a front perspective view of the air filtration device illustrated in FIG. 9, with the filter inserted properly;

FIG. 11 is a partial perspective view of the air filtration device similar to the device in FIG. 1, illustrating an alternative embodiment of a filter change indicator;

FIG. 12 is a cross-sectional view of the air filtration device taken along line 12—12 in FIG. 11;

FIG. 13 is a partial rear elevational view, with a partial cut-away, of the air filtration device of FIG. 11, illustrating the alternative embodiment of the filter change indicator; and

FIG. 14 is a partial exploded view of the filter change indicator of FIG. 11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to the drawings and, more particularly to FIGS. 1, 2 and 3, an air filtration device for intake of atmospheric air, filtration of the atmospheric air and emission of filtered air is illustration generally at 10 and includes a housing 12. The housing 12 includes a generally curved side wall 28 fixed to a generally flat front portion 29. A generally planar door 18 is fixed to the flat front portion 29, using hinges 19 as seen in FIG. 3. Referring back to FIG. 1, the door 18 includes a front surface 14 and a generally circular perforated air inlet grill 16. Tabs 20 are provided on each side of the door as seen in FIGS. 1 and 2, for ease of opening for filter replacement, as will be seen in greater detail hereinafter. The door covers approximately 80% of the front surface of the device 10. The remainder of the front surface is covered by a control panel 22. This ratio is primarily a function of aesthetics, and does not effect the performance of the device 10. A centralized rocker 24 is provided in the control panel 22 to control an internal switch to activate and deactivate the device 10 and an indicator light 26 is provided above the rocker switch 24 which illuminates when the device 10 is activated and, as will be seen in greater detail hereinafter, flashes when the filtration device 10 has been in operation for a predetermined time period. A plurality of vents 30 are provided around the curved side surface 28 to act as air outlets.

Turning now to FIG. 3, a rear surface 32 is provided adjacent and integral with the side surface 28. The rear surface 32 is curved to conform to the shape of the side surface 28.

In order to facilitate electrical power application, a pair of electrical prongs 34 extend outwardly from the rear surface 32 for operational engagement with a conventional electrical outlet. The electric prongs 34 are each formed of like dimensions, so that the air filtration device may be connected to an electrical outlet without regard to the dimensional differences between the socket openings. Accordingly, the device 10 may be oriented properly, with the prongs 34 above the vents 30, no matter what orientation a polarized socket is mounted to the outlet E. Further, the prong arrangement allows the device 10 to be mounted in the lower of the two sockets in an outlet pair, without regard to the dimensional differences between the socket openings. The location of the prongs 34 with respect to the top of the housing 12 ensures that the uppermost socket in a socket pair will remain available for use by other devices when the device 10 is in operation, as seen in FIG. 8.

A bumper member 36 is provided below the electrical prongs 34 for abutment with a vertical surface or wall W against which the device 10 is mounted, as seen in FIGS. 7 and 8. The bumper member 36 assists a user in orienting the device 10 with respect to a wall surface W. Further, the bumper member 36 may be formed from resilient material. A resilient bumper member 36 absorbs and dampens vibrations from the housing 12 to reduce or prevent their transmission to the wall W which reduces the noise associated with an operational air filtration device 10.

Turning now to FIGS. 4, 5 and 6, the internal components of the device 10 are illustrated. It will be appreciated that in order to filter air, an air flow path is defined through the housing 12, a filter 40 is provided and a device is provided to move the air. As seen in FIG. 5, the air flow path, illustrated by arrows, is defined by air movement generated within the device 10, from the air inlet 16, through the device 10 and outwardly through the vents 30. An impeller 54 is provided to move air through the device 10. The impeller 54 is a basket-like structure having two mounting rings 55 separated by a plurality of vanes 57 that are curved to draw air from outside the impeller 54 and drive the air outwardly through the side of the impeller 54.

The impeller 54 is rotated by an electric motor 46. As seen in FIG. 5, the motor 46 includes an armature 56 attached to the impeller 54. Electrical excitation of the motor 46 causes the armature 56 to rotate, thereby rotating the impeller 54.

As also seen in FIGS. 4, 5 and 6, a filter 40 is provided for filtering incoming air. The filter 40 can be directional in that a particular surface can be facing incoming air so that contaminated air is drawn through the filter 40 in a direction optimal for air filtration. One useful filter 40 includes a front filtration surface 41, a rear scrim 43 and is charcoal activated. It will be appreciated by those skilled in the filtration art that other filter compositions may be used. In particular, some filters may be configured to remove bathroom odors and some filters may be configured to remove kitchen odors. Other types of filters may include an increased charcoal content for smoke filtration. It is contemplated that various types of filters may be used with the present air filtration device 10 without reducing the effectiveness of any of the filters or the overall filtering efficacy of the device 10. The filter 40 is formed with a notch 42 in one corner, as will be explained in greater detail hereinafter.

An internal baffle plate 60 is provided to provide a surface for mounting the filter 40 and to direct air inwardly toward the impeller. A conical inner surface 62 is provided in the baffle plate 60 to provide a nozzle effect to increase the effectiveness of the filtration device 10. A locating surface 43 is formed as a raised rib in a lower corner of the baffle plate 60 corresponding to the notch 42 in the filter 40 for orienting the filter in the housing 12. An icon 44 is applied to the baffle plate 60 adjacent the locating surface 43, for visual indication of proper filter orientation. As also illustrated in FIG. 4, the air filtration device 10 is configured for mounting against an electrical outlet E mounted on a wall W.

As seen in FIGS. 5 and 6, the air flow path is defined through the housing 12 and illustrated by arrows. Atmospheric air enters the air filtration device 10 through the air inlet grill 16 and then travels through the filter 40 for contaminant removal. With reference to FIG. 4, the air travels down the conical inner surface 62 fo the internal baffle plate 60 and enters a plenum 63 containing the rotating impeller 54. The impeller 54 draws the air along the flow path to an area within the rotating vanes 57 and the air is directed then outwardly through the rotating vanes 57 through the plenum 63 and eventually out through the vents 30 in the curved side wall 28.

Another feature of the present invention is a filter change indicator providing the ability to determine in general when the filter 40 should be replaced. Under normal operation, the filter 40 should be replaced after a predetermined period of time. It may be presumed that the time period of filter contamination coincides with the operating period of the impeller 54 and therefore the motor 46. In a first embodiment of the filter change indicator, a timing circuit 48 is provided in the wiring 50 that connects the switch 25 to the motor 46. As also seen in FIGS. 5 and 6, the rocker 24 operates a remotely disposed switch 25, with the rocker 24 projecting through the control panel 22. It should be appreciated by those skilled in the art that such a timing circuit is a basic electronic device and can be configured in any number of ways. The timing circuit is also in electrical communication with the indicator lamp 26 which illuminates upon electrical excitation of the motor 46. When the timing circuit 48 has reached the end of a predetermined time period, the indicator light 26 is caused to pulsate, or flash, which is an indication that the filter 40 should likely be replaced. The timing circuit 48 also includes a reset switch 49 which allows an operator or owner to reset the timer once the filter is replaced.

Optionally, the device 10 may be provided without a timing circuit 48 as illustrated in FIG. 6. In such a case, a second or mechanical filter change indicator, as illustrated in FIGS. 11-14, may be utilized. More particularly, an indicator member is movably supported by the housing 12 and preferably comprises a date wheel 64 rotatably supported intermediate the control panel 22 and the flat front portion 29 of the housing 12. The date wheel 64 includes a substantially cylindrical outer wall 66 defining a substantially annular indicia ring 68 supported for rotation about a longitudinal center axis 69. Indicia 70, preferably symbols representing months of the year arranged in successive chronological order, are supported on an outer surface 72 of the indicia ring 68. The outer wall 66 further defines a substantially annular gripping ring 74 includes disposed relative to the indicia ring 68. The gripping ring 74 concludes a gripping surface, most preferably in the form of a plurality of alternating projections 76 and recesses 78 for providing improved frictional engagement or gripping of the date wheel 64 by a user and thereby facilitating rotational movement of the wheel 64.

A spacing wall 80 extends peripherally around the flat front portion 29 of the housing 12 in a forward direction toward the control panel 20 and the door 18. The spacing wall 80 includes an upper portion 82 having a viewing window 84 formed therein. A portion of the indicia ring 68 is visible through the viewing window 84 thereby permitting the user to view a limited portion of the indicia 70 therethrough. A portion of the annular gripping ring 74 preferably extends upwardly through the viewing window 84 for facilitating engagement by a user. A pointer 86 is preferably formed within an upper surface of a control panel 22 for alignment with one of the indicia 70, thereby facilitating reading of the appropriate symbol within the viewing window 84.

The date wheel 64 is rotatably supported on an axial 90 extending rearwardly from an inner surface of the control panel 22. The axle 90 passes through an aperture 92 formed within the baffle plate 60. A semi-annular recess is formed within the baffle plate concentrically with respect to the aperture 92 first guiding ring 96 extending frontwardly from the date wheel 64. As may be appreciated, receipt of the first guiding ring 96 within the recess 94 facilitates relative positioning of the date wheel 64 relative to the baffle plate 60. The axle 90 is received within an aperture 98 formed within the date wheel 64 concentrically relative to the outer wall 66.

An annular second guiding ring 100 extends rearwardly from the date wheel 64 and is concentrically received within a counterbore 102 formed within a post 104 extending forwardly from an inner surface of the front portion 29 of the housing 12. Receipt of the ring 100 within the bore 102 further assists in proper location of the date wheel 64 within the housing 12. It should be further noted that a conventional fastener, such as a screw 106, passes through a bore 108 in the post 104, and is threadably received within a threaded bore 110 of the axle 90. As such, the screw 106 secures the date wheel 64 and baffle plate 60 intermediate the housing 12 and control panel 22.

An indexing device 112 is operably associated with the date wheel 64 for rotationally and releasably retaining the date wheel 64 in one of a plurality of set positions. The set positions are associated with the indicia 70 supported by the date wheel 64. In the preferred embodiment, each set position is associated with one of the symbols representing the months of the year. The indexing device 112 includes a plurality of radially outwardly extending indexing recesses 114 formed within a substantially cylindrical inner wall 116. The inner wall 116 is concentrically disposed within the outer wall 66. A resilient finger 118 extends frontwardly from the inner surface of the front portion 29 of the housing 12 and is receivable within any one of a plurality of indexing recesses 114 for releasably securing the date wheel 64 in one of the set positions and preventing inadvertent rotation therefrom. More particularly, the indexing finger 118 is biased radially outwardly relative to the inner wall 116 such that the finger 118 is securable within the recesses 114.

In operation, it may be readily appreciated that positioning of the date wheel 64 relative to the viewing window 84, and more particularly with respect to the pointer 86, alters the particular indicia 70 visible to the user. The user simply rotates the date wheel 64 to a desired time as represented by the indicia 70 for projected filter replacement. The particular month appearing within the window 84 serves to remind the user when the filter 40 requires replacement.

Referring now to FIGS. 7 and 8, in operation, the air filtration device 10 of the present invention is plugged into an electrical outlet using electrical prongs 34 in a generally conventional manner. The rear surface 32 of the housing 12 is closely adjacent to the electrical outlet E and may abut the electrical outlet E. The bumper member 36 abuts the wall W or outlet E or indeed, any vertical surface to which the device 10 may be fixed in order to provide proper orientation of the device 10 with respect to the wall surface W and, if the bumper member 36 is resilient, to provide a damping effect for motor vibrations that may be transmitted from the housing 12 during operation. Once a device 10 is against the wall W the rocker 24 is moved into an “on” position, which causes the switch 25 to provide electrical excitation to the motor 46 which, in turn, causes the impeller 54 to rotate, thereby drawing atmospheric air inwardly through the air inlet grill 16. The atmospheric air is drawn through the filter 40, and is caused to travel along the air flow path as defined in FIGS. 5 and 6. As the air passes through the filter 40 contaminants are removed and the filtered air travels intermediate the vanes 57 of the impeller 54 and is expelled through the vents 30 formed in the curved side surface 28. As seen in FIG. 7, and as will be appreciated by those skilled in the art, the filtered air is dispersed along an approximately 315° curve and the wall W acts as a baffle to enhance air dispersion from the device 10. Therefore, the air filtration device 10 of the present invention draws air from a generally focused source of contaminated air and provides a dispersed wave of filtered air to enhance the effectiveness of the filter operation. It should be noted that the relationship of the device 10 and the wall LW, along with the vent location, is illustrated in FIG. 8.

As previously stated, the present invention provides a user with visual enhancements with respect to filter replacement. With reference to FIG. 9, a filter is shown spaced a distance from the baffle plate 60 to which it is to be mounted. As can be seen, the filter 40 includes a notch 42 formed in a lower right hand corner of the filter 40. The baffle plate 60 includes the icon 44 which is preferably shaped as a keyhole, yet may be shaped in any configuration imaginable. By orienting the notch 42 when the filter 40 is in place, as seen in FIG. 10, the filter 40 is oriented properly with respect to air flow. Should the filter 40 be inserted in a reverse manner, the icon 44 would not be visible, because the notch 42 would not be in a position to allow the user to see the icon 44. Additionally, the locating surface 43 acts to physically orient the filter 40. Therefore, the combination of the notch 42, the icon 44, and the locating surface 43 allows someone replacing the filter to easily determine when the filter is in proper orientation with respect to air flow.

By the above, the present invention provides a compact air filtration device that provides enhanced effectiveness, the ability to determine when a filter should be replaced, and a visual indication of proper filter orientation with respect to air flow.

It will therefore be readily understood by those persons skilled in the art that the present invention is susceptible of a broad utility and application. Many embodiments and adaptations of the present invention other than those herein described, as well as many variations, modifications and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing description thereof, without departing from the substance or scope of the present invention. Accordingly, while the present invention has been described herein in detail in relation to its preferred embodiment, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for purposes of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended or to be construed to limit the present invention or otherwise to exclude any such other embodiments, adaptations, variations, modifications and equivalent arrangements, the present invention being limited only by the claims appended hereto and the equivalents thereof. 

What is claimed is:
 1. An air filtration device for intake of atmospheric air, removal of contaminants from the atmospheric air, and expulsion of filtered air, said air filtration device comprising: a housing defining an air flow path; an air inlet formed in said housing; an air outlet formed in said housing in spaced relation to said air inlet, said air flow path extending between said air inlet and said air outlet; a filter located in said air flow path; and a filter change indicator including an indicator member movably supported by said housing, indicia supported by at least one of said indicator member and said housing for selective positioning relative to the other of said housing and said indicator member at one of a plurality of set positions, each said indicia indicating time and associated with one of said set positions wherein the positioning of said indicator member relative to said housing provides an indication of when said filter should be replaced.
 2. The air filtration device of claim 1 further comprising: an impeller for moving air through said housing along said air flow path from said air inlet to said air outlet; and a motor operably connected to said impeller.
 3. The air filtration device of claim 2 further comprising a pair of electric prongs extending outwardly from said housing for operational engagement with an electrical wall outlet for supplying electrical power to said motor.
 4. The air filtration device of claim 1 wherein said indicia comprise symbols representing months of a calendar year arranged in successive chronological order.
 5. The air filtration device of claim 1 wherein said indicator member comprises a wheel rotatably supported by said housing and including a peripheral outer surface supporting said indicia.
 6. The air filtration device of claim 5 wherein said housing further includes a viewing window, a portion of said indicia supported by said outer surface of said wheel visible through said viewing window.
 7. The air filtration device of claim 5 further comprising an indexing device operably associated with said wheel for releasably retaining said wheel from rotational movement in one of said plurality of set positions relative to said housing.
 8. The air filtration device of claim 7 wherein said indexing device comprises a resilient finger supported by said housing and a plurality of circumferentially spaced indexing recesses formed within said wheel for receiving said finger.
 9. The air filtration device of claim 5 wherein said wheel comprises an annular indicia ring defining said peripheral outer surface supporting said indicia, and an annular gripping ring coaxlely disposed relative to said indicia ring and including an outer peripheral surface having a plurality of alternating projections and recesses for facilitating gripping of said wheel.
 10. An air filtration device for intake of atmospheric air, removal of contaminants from the atmospheric air, and expulsion of filtered air, said air filtration device comprising: a housing; an air flow path extending within said housing; a filter located within said air flow path; a date wheel rotatably supported by said housing, said date wheel including an annular indicia ring having an outer peripheral surface, indicia supported by said outer peripheral surface for selective positioning relative to said housing at one of a plurality of set positions, each said indicia indicating time and associated with one of said set positions; and an indexing device operably associated with said date wheel for rotationally and releasably retaining said wheel in one of said plurality of set positions, wherein the positioning of said date wheel relative to said housing provides an indication of when said filter should be replaced.
 11. The air filtration device of claim 10 wherein said indicia comprise symbols representing months of a calendar year arranged in successive chronological order.
 12. The air filtration device of claim 10 wherein said housing further includes a viewing window, a portion of said indicia ring visible through said window.
 13. The air filtration device of claim 10 wherein said indexing device comprises a resilient finger supported by said housing and a plurality of circumferentially spaced indexing recesses formed within said date wheel for receiving said finger.
 14. The air filtration device of claim 13 wherein said date wheel further includes a substantially cylindrical inner wall, said indexing recesses extending substantially radially outwardly within said inner wall, and said finger biased substantially radially outwardly relative to said inner wall for releasable engagement with said indexing recesses.
 15. The air filtration device of claim 14 wherein said date wheel further comprises a substantially cylindrical outer wall concentrically disposed relative to said inner wall, said indicia ring defined by said outer wall.
 16. The air filtration device of claim 15 wherein said date wheel further comprises an annual gripping ring defined by said outer wall, said gripping ring including an outer peripheral surface having a plurality of alternating projections and recesses for facilitating gripping of said wheel. 